Can you trust fuel economy stats from auto makers?

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Hello: I really love reading your articles. I just bought a Grand Cherokee Laredo and I really like it. I did my homework before buying this car. The only thing that disappoints me is the gas consumption. Transport Canada says that the fuel economy for this car is 13.1 litres/100 km city and 8.9 highway. I have been very careful this month driving this car economically, keeping on the ECO message on the electronic information display. The best value I got so far is 11.1 highway (no traffic at all with 95 km/h) and an average of 14.8 on city/highway driving. Doesn't anybody care about the fuel economy numbers they advertise? - L. in Toronto

Cato: Do the car companies care about advertised fuel economy numbers? Yes, of course. Nailing great fuel-efficiency numbers is a pride point, something to tout.

Ford, for instance, says its new models will all deliver best-in-class fuel numbers. Hyundai claims to have the most fuel-efficient fleet in North America. Honda says it plans to reclaim the fuel-efficiency crown. General Motors goes to great lengths to say the Chevy Equinox crossover has the best highway fuel economy in its class. Chrysler says its new V-6 Dodge Durango SUV is more fuel-efficient with the new Pentastar V-6 engine than the old Chrysler Aspen Hybird SUV.

And on and on.

Vaughan: I think you've missed L's point, Cato. And that point is this: the posted fuel economy numbers don't match reality.

Cato: Yes, I get that point, too. Real world fuel economy absolutely differs from the sticker numbers. That's why Natural Resources Canada and Transport Canada - who both post fuel economy numbers and offer fuel savings ideas on their respective web sites - clearly state that the numbers are useful in comparing various vehicles; they are not useful for establishing the real-world fuel economy you will get in daily driving.

Vaughan: In other words, the EnerGuide fuel consumption ratings bear no resemblance to reality.

Cato: I think I said that.

Vaughan: We have an expensive army of civil servants with pencils and clipboards standing around some Ottawa lab cranking out bewildering numbers that no one believes. If you want to get some real numbers based on real driving, don't ask a bunch of civil servants for it. Count on some good old, car-driving journos to give you the truth.

Cato: Hang on, now. There's more to this story. You see, no one in Ottawa actually tests all the vehicles in Canada for fuel economy. Instead, the car companies submit their numbers and Ottawa accepts them, though there is some selective verification - sort of like the random extra searches you see at the security stations at airports.

Vaughan: Which goes even more to my point. L, if you want real-world fuel economy numbers, go to the journos. The most comprehensive batch of numbers can be found at edmonds.com. Their long-term testing programs record actual on-the-road fuel consumption.

Each vehicle gets about 20,000 miles (remember they're American) of driving by a whole range of different drivers in different conditions. They average it all out and, bingo, there's a fuel economy number you can believe. And, L, be sure to pay your taxes on time.

Cato: Gotta get that little Ottawa shot in there. He's been listening to that idiot Rush Limbaugh again.

Look, there is such a thing as the scientific method and that's why laboratory tests are conducted - to control the variables. It's more important to have valid comparisons than to make a guess based on a bunch of random driving. Just remember that most of the actual testing is done by car companies, who then submit their numbers to government for approval.

Vaughan: Laboratory, schlaboratory. The law of averages, Cato. Get a big enough sample and the variables will control themselves. It's why we don't need a long-form census.

Cato: Oh, no. Now I know, Vaughan's watching Fox News, too.

Vaughan: Look, our man L likes his Jeep and he should. It's one of the first new things since Fiat came in after the Chrysler bankruptcy and I think it's a sign of more good things to come. I assume from the numbers he's quoting he must be driving the version with the new Pentastar V-6. He likes his vehicle. What he doesn't like are the stupid numbers the government gave him.

Cato: But if you don't like the gasoline fuel economy, L, you might try diesel for your next SUV, or a hybrid. The Mercedes-Benz ML350 BlueTec is one option, another is the Lexus RX450h hybrid. The problem is, these two are $12,000-$13,000 more expensive than L's Grand C Limited.

Vaughan: For now, L, go easy on the gas pedal and keep it until Chrysler gets a decent diesel or hybrid.

Cato: I see you remembered L likes his Jeep.

Vaughan: Yes, but he just doesn't like stupid numbers from a bunch of make-believe tests, and neither do I.

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HOW THEY COMPARE

Source: car manufacturers

Jeremy Cato and Michael Vaughan are co-hosts of Car/Business, which appears Fridays at 8 p.m. on Business News Network and Saturdays at 11:30 a.m. on CTV.

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